Tachograph for a motor vehicle, paper strip for a tachograph and method for aligning a longitudinally displaceable paper strip with respect to a printing device in a tachograph

ABSTRACT

A paper strip ( 6 ) for a tachograph ( 1 ) has a series of marks ( 17, 18 ) which extend transversely with respect to its direction of movement in the tachograph ( 1 ). The marks ( 17, 18 ) are of different lengths and are sensed by a sensor ( 10, 11 ). The sensor ( 10, 11 ) generates a signal sequence which provides definitive information about an offset of the paper strip ( 6 ) in the printing unit ( 7 ). A control device ( 12 ) actuates a printing unit ( 7 ) of the tachograph ( 1 ) and compensates for the offset.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage Application of InternationalApplication No. PCT/EP2007/054512 filed May 10, 2007, which designatesthe United States of America, and claims priority to German ApplicationNo. 10 2006 023 984.9 filed May 22, 2006, the contents of which arehereby incorporated by reference in their entirety.

TECHNICAL FIELD

The invention relates to a tachograph for a motor vehicle, with areceptacle for a paper strip, with a printing unit for issuing data inprecisely designated positions in relation to a reference line of aregion to be printed, which reference line extends longitudinally overthe paper strip in the designated direction of movement, with a drivingdevice for driving the paper strip, and with an electronic controldevice for actuating the printing unit and the driving device. Theinvention furthermore relates to a paper strip for a tachograph, with aregion which is to be printed and with a reference line extendinglongitudinally over the paper strip. The invention furthermore relatesto a method for aligning a longitudinally displaceable paper strip withrespect to a printing device in a tachograph, in which the printingdevice is aligned with respect to a reference line of a region to beprinted, which reference line extends longitudinally over the paperstrip.

BACKGROUND

Known typing devices for issuing data stored in a tachograph generallyhave a pin-feed platen, the pins of which penetrate edge perforations ofthe paper strip and ensure the feeding of the paper strip under theprinting unit. The paper strip is generally coiled up on a paper reel.The edge perforation of the paper strip serves to align the printingunit in relation to the region which is to be printed and on which agrid network is generally arranged. In addition, the edge perforationreduces the slippage during the driving of the paper strip. When a newpaper reel is inserted, the printing unit is adjusted to a referenceposition with respect to the region to be printed. The adjustment isintended to ensure that the data, for example a graphical depiction ofthe driving speed of the motor vehicle, are transmitted over time in thedesignated positions on the grid network.

However, a drawback of the known tachograph and of the known paper reelis that tolerances may occur between the printing unit and the visiblegrid network of the region of the paper reel that is to be printed, andtherefore the position of the data with respect to the visible gridnetwork is not reliably ensured. Such tolerances may lie in thecomponents of the tachograph itself, for example because of aninclination of the pin-feed platen, or in the position of the printingunit. Furthermore, tolerances may occur due to geometrical fluctuationsin the paper dimensions or in the optically visible grid network.Furthermore, such tolerances may also occur due to the paper stripabsorbing moisture during operation of the tachograph.

SUMMARY

A tachograph of the type mentioned at the beginning can be designed insuch a manner that a reliable alignment of the printing unit withrespect to the reference line of the region to be printed is ensured.Furthermore, a paper strip can be provided for a tachograph of thistype, said paper strip ensuring reliable alignment in the tachographwith respect to the reference line of the region to be printed.Furthermore, a method for aligning the paper strip with respect to theprinting unit of the tachograph can be provided, said method permittinga reliable assignment of the data printed out from the tachograph withrespect to the reference line of the paper strip.

According to an embodiment, a tachograph for a motor vehicle, maycomprise a receptacle for a paper strip, a printing unit for issuingdata in precisely designated positions in relation to a reference lineof a region to be printed, which reference line extends longitudinallyover the paper strip in the designated direction of movement, a drivingdevice for driving the paper strip, and an electronic control device foractuating the printing unit and the driving device, wherein a sensor isconnected to the control device, the sensor is designed for sensing aseries of marks which extend to different distances transversely withrespect to the reference line and for generating signal sequencescorresponding to the sensed marks, and wherein the control device isdesigned for actuating the position of the printout of the printing unittransversely with respect to the reference line of the paper strip as afunction of the signal sequence of the sensor.

According to a further embodiment, the sensor may be arranged on a sideof a paper guide of the paper strip, which side lies opposite theprinting unit. According to a further embodiment, a respective sensorfor sensing marks of the paper strip can be arranged on bothlongitudinal sides of the paper strip, and wherein the control device isdesigned for determining a width extent of the paper strip as a functionof the signal sequences of the sensors. According to a furtherembodiment, the sensor can be operable to detect optical, magnetic,inductive or electric marks. According to a further embodiment, thesensor may have a laser and may be operable to detect reflections of thelaser.

According to another embodiment, a paper strip for a tachograph, maycomprise a region which is to be printed and a reference line extendinglongitudinally over the paper strip, wherein marks provided for sensingby the sensor of the tachograph are arranged in a designated positionwith respect to the reference line and extend to different distancestransversely with respect to a designated direction of movement.

According to a further embodiment, the marks can be arrangedperiodically with respect to one another and are of different lengths.According to a further embodiment, the marks can be arranged on the rearside of the region to be printed. According to a further embodiment, themarks can be arranged on two longitudinal sides of the paper strip.

According to another embodiment, a method for aligning a longitudinallydisplaceable paper strip with respect to a printing unit in atachograph, may comprise the steps of: aligning the printing unit withrespect to a reference line of a region to be printed, which referenceline extends longitudinally over the paper strip, and sensing a seriesof marks which are arranged on the paper strip transversely with respectto the direction of movement and are of different lengths by a sensor,wherein a control device detects an offset of the printing unit withrespect to the reference line from the signal sequence of the sensor andactuates the printing unit in order to compensate for the offset.

According to a further embodiment, a line can be printed out during afirst adjustment of the printing unit of the tachograph with respect tothe reference line of the paper strip, in that an offset of the linewith respect to the reference line is measured and is input into thecontrol device, and in that the control device compensates for themeasured offset during the actuation of the printing unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention permits numerous embodiments. To further clarify its basicprinciple, one of these is illustrated in the drawing and is describedbelow. In the drawing

FIG. 1 shows a longitudinal section through a tachograph according to anembodiment,

FIG. 2 shows a front side of a paper strip of a paper reel for thetachograph from FIG. 1,

FIG. 3 shows a rear side of the paper strip from FIG. 2 with sensors ofthe tachograph from FIG. 1,

FIG. 4 shows, on a greatly enlarged scale, a series of marks arranged onthe rear side of the paper strip,

FIGS. 5 a, 5 b show two diagrams of signal sequences of a sensor sensingthe series of marks in different positions.

DETAILED DESCRIPTION

According to an embodiment, the sensor can be designed for sensing aseries of marks which extend to different distances transversely withrespect to the reference line and for generating signal sequencescorresponding to the sensed marks, and in that the control device isdesigned for actuating the position of the printout of the printing unittransversely with respect to the reference line of the paper strip as afunction of the signal sequence of the sensor.

This design enables the control device to align the printing unit usingthe signal sequence of the sensor. Since the signal sequence of thesensor is dependent on the marks detected, and the marks detected extendto different distances transversely with respect to the reference lineand therefore with respect to the direction of movement of the paperstrip, different numbers of marks are sensed as a function of theposition of the paper strip with respect to the sensor. This results ina signal sequence corresponding to the position of the paper strip withrespect to the printing unit. The printing unit can therefore be alignedparticularly reliably with respect to the reference line of that regionof the paper strip which is to be printed, and can preferably keep acurved profile, which is to be printed out by the printing unit, of theprintout continuously at the designated alignment with respect to thereference line.

Restriction of the freedom of movement of the printing unit over theregion to be printed because of the sensor can be avoided in a simplemanner, according to another embodiment, if the sensor is arranged on aside of a paper guide of the paper strip, which side lies opposite theprinting unit. By this means, one side of the paper strip is providedexclusively for issuing the data while the other side can have the marksfor the sensor.

Swelling of the paper strip, for example due to absorption of moisture,may result in an enlargement of the region to be printed. This resultsin an erroneous issuing of the data in the event of a grid network beingarranged on that region of the paper strip which is to be printed.According to an embodiment, swelling of the paper strip can be takeninto consideration in a simple manner during the issuing of the data ifa respective sensor for sensing marks of the paper strip is arranged onboth longitudinal sides of the paper strip, and if the control device isdesigned for determining a width extent of the paper strip as a functionof the signal sequences of the sensors. In this case, the control devicecan prepare a graphic, which is to be printed out, in such a mannerthat, if the paper strip becomes wider, the graphic which is to beprinted out is stretched or, if the paper width becomes smaller, iscompressed.

The tachograph according to an embodiment turns out to be particularlysimple structurally if the sensor is designed for detecting optical,magnetic, inductive or electric marks.

The sensor could have, for example, a cost-effective reflex lightbarrier. However, according to another embodiment, the sensor hasparticularly high resolution if the sensor has a laser and is designedfor detecting reflections of the laser. By this means, the accuracy ofthe alignment of the printing unit with respect to the paper strip isfurther increased.

The problem mentioned second, namely the provision of a paper strip forsuch a tachograph, the paper strip ensuring reliable alignment in thetachograph with respect to the reference line of the region to beprinted, is solved according to an embodiment in that marks provided forsensing by the sensor of the tachograph are arranged in a designatedposition with respect to the reference line and extend to differentdistances transversely with respect to a designated direction ofmovement.

By means of this design, the marks are arranged on the paper strip and,by means of the sensing of the sensor arranged in the tachograph, permita reliable alignment of the reference line with respect to the printingunit.

The data to be issued can therefore be plotted onto the region to beprinted in a particularly reliable manner with respect to the referenceline.

According to an embodiment, the marks are constructed in a particularlysimple manner if the marks are arranged periodically with respect to oneanother and are of different lengths.

Disturbance of the transmitted data by the marks can be avoided in asimple manner, according to an embodiment, if the marks are arranged onthe rear side of the region to be printed.

Swelling of the paper strip, for example due to effects of moisture, canbe detected in a simple manner by means of two sensors arranged in thetachograph if the marks are arranged on two longitudinal sides of thepaper strip.

The problem mentioned third, namely the provision of a method foraligning the paper strip with respect to the printing unit of thetachograph, the method permitting reliable assignment of the dataprinted out from the tachograph with respect to the reference line ofthe paper strip, is solved according to an embodiment in that a seriesof marks which are arranged on the paper strip transversely with respectto the direction of movement and are of different lengths is sensed by asensor, in that a control device detects an offset of the printing unitwith respect to the reference line from the signal sequence of thesensor and actuates the printing unit in order to compensate for theoffset.

By means of this design, the position of the paper strip is determinedusing the signal sequence of the sensor, and, using the signal sequence,the printing unit is actuated and aligned over the reference line. Bythis means, tolerances between the printing unit and the reference lineare compensated for and therefore a reliable assignment of the dataprinted out from the tachograph with respect to the reference line isensured. In this case, the alignment of the printing unit in accordancewith the signal sequence of the sensor can take place continuously or atshort cyclical time intervals. A curved profile, which is to be printedout by the printing unit, of the printout can therefore preferably bekept continuously at the designated alignment with respect to thereference line.

According to another embodiment, manufacturing tolerances of theprinting unit can be compensated for in a simple manner if a line isprinted out during a first adjustment of the printing unit of thetachograph with respect to the reference line of the paper strip, if anoffset of the line with respect to the reference line is measured and isinput into the control device, and if the control device compensates forthe measured offset during the actuation of the printing unit. In thesimplest case, the control device adds the offset measured during thefirst adjustment to the offset determined during operation of thetachograph.

FIG. 1 shows, schematically in a longitudinal section, a tachograph 1for a motor vehicle, with a front panel 2. The tachograph 1 has amagazine 3 with a paper reel 4 and a motorized driving device 5 fortransporting a paper strip 6 wound on the paper reel 4. The tachograph 1furthermore has a printing unit 7 for printing the paper strip 6 of thepaper reel 4. In order to simplify the drawing, of the printing unit 7only a printing roller is illustrated. The paper strip 6 of the paperreel 4 is guided from the magazine 3 in a paper guide 8 over theprinting unit 7 to a gap 9 in the front panel 2. The paper strip 6printed by the printing unit 7 is issued through the gap 9 in the frontpanel 2 and can be torn off. Sensors 10, 11 for detecting the positionand the width of the paper strip 6 in the paper guide 8 are alsoarranged on the paper guide 8. The sensors 10, 11 are arrangedconsecutively, as illustrated in FIG. 3. The sensors 10, 11, themotorized driving device 5 and the printing unit 7 are connected to anelectronic control device 12. The control device 12 actuates theprinting unit 7 and the driving device 5 as a function of the signals ofthe sensors 10, 11. This enables the position of the printing unit 7 tobe aligned with respect to the position of the paper strip 6.

FIG. 2 shows a partial region of the paper strip 6 of the paper reel 4from FIG. 1 with a region 13 which is to be printed by the printing unit7. The region 13 which is to be printed has a visible grid network 14,which is designed in the form of a grid, and a reference line 15extending in the longitudinal direction of the paper strip. In addition,the printable region is delimited by a scale 16 arranged transverselywith respect to the reference line 15. The reference line 15 can beprovided, for example, with a time axis while the scale 16 indicates thedriving speed of the motor vehicle. The direction of movement of thepaper strip 6 in the tachograph 1 takes place in the direction of thereference line 15.

FIG. 3 shows a rear side of the paper strip 6 from FIG. 2 and,schematically, the sensors 10, 11 of the tachograph from FIG. 1. On therear side of the paper strip 6, a respective series of marks 17, 18detected by the sensors 10, 11 are arranged on both longitudinal sides.It can be seen in this case that the marks 17, 18 are arrangedtransversely with respect to the longitudinal direction of the paperstrip 6. It is essential for the marks 17, 18 that they are arranged ina reference line with a high degree of accuracy with respect to thefront side, which is illustrated in FIG. 2. The shape of the marks 17,18 is illustrated on a greatly enlarged scale in FIG. 4. A visible colormark 19 which indicates the near end of the paper reel 4 is arranged atthe end of the paper strip 6.

FIG. 4 shows, on a greatly enlarged scale, one of the series of marks17, 18 from FIG. 3. It can be seen in this case that the marks 17, 18are designed to be of different lengths and extend to differentdistances transversely with respect to the longitudinal direction of thepaper strip 6.

Two possible positions of the sensors 10, 11 over the marks 17, 18 arearranged at Va and Vb. FIG. 5 a represents a signal sequence S of thesensors 10, 11 over the time t, which signal sequence is supplied by thecorresponding sensor 10, 11 when it is located in position Va over theseries of marks 17, 18 and the driving device 5 drives the paper strip6. By contrast, FIG. 5 b shows the signal sequence S over the time t,which signal sequence is supplied by the corresponding sensor 10, 11when it is in position Vb over the marks 17, 18.

During operation of the tachograph 1 for the first time, with the firstadjustment of the printing unit 7 on the paper strip 6 a line is printedout and the signal sequence of the sensors 10, 11 measured. For example,the signal sequence illustrated in FIG. 5 a is produced during themeasurement. Furthermore, the offset of the line with respect to thereference line 15 is measured and the printing unit 7 is adjusted viathe control device 12 or manually in such a manner that, during afollowing printout, the line is printed, for example, directly on thereference line 15. The printing unit 7 is therefore adjusted withrespect to the region 13 to be printed. If, during operation or afterthe paper reel 4 has been changed, the sensors 10, 11 generate adifferent signal sequence, for example the signal sequence illustratedin FIG. 5 b, the offset of the paper strip 6 in relation to the printingunit 7 can be determined in the control device 12 as a function of thedimensions of the marks 17, 18. The control device 12 subsequentlyactuates the printing unit 7 in such a manner that the offset iscompensated for. The printout by the printing unit 7 therefore takesplace in a manner offset by the offset determined in relation to theprintout after the first adjustment. The second series of marks 17, 18illustrated in FIG. 3 serves to detect the width of the paper strip 6.Since the width of the paper strip 6 can vary, for example as a functionof the moisture, a stretched printout takes place by the printing unit 7in the event of the paper strip 6 becoming wider and a compressedprintout in the event of the paper strip 6 becoming smaller.

1. A tachograph for a motor vehicle, comprising a receptacle for a paperstrip, printing unit for issuing data in precisely designated positionsin relation to a reference line of a region to be printed, whichreference line extends longitudinally over the paper strip in thedesignated direction of movement, a driving device for driving the paperstrip, and an electronic control device for actuating the printing unitand the driving device, wherein a sensor is connected to the controldevice, the sensor is designed for sensing a series of marks whichextend to different distances transversely with respect to the referenceline and for generating signal sequences corresponding to the sensedmarks, and wherein the control device is designed for actuating theposition of the printout of the printing unit transversely with respectto the reference line of the paper strip as a function of the signalsequence of the sensor.
 2. The tachograph according to claim 1, whereinthe sensor is arranged on a side of a paper guide of the paper strip,which side lies opposite the printing unit.
 3. The tachograph accordingto claim 1, wherein a respective sensor for sensing marks of the paperstrip is arranged on both longitudinal sides of the paper strip, andwherein the control device is designed for determining a width extent ofthe paper strip as a function of the signal sequences of the sensors. 4.The tachograph according to claim 1, wherein the sensor is operable todetect optical, magnetic, inductive or electric marks.
 5. The tachographaccording to claim 1, wherein the sensor has a laser and is operable todetect reflections of the laser.
 6. A paper strip for a tachograph,comprising a region which is to be printed and a reference lineextending longitudinally over the paper strip, wherein marks providedfor sensing by the sensor of the tachograph are arranged in a designatedposition with respect to the reference line and extend to differentdistances transversely with respect to a designated direction ofmovement.
 7. The paper strip according to claim 6, wherein the marks arearranged periodically with respect to one another and are of differentlengths.
 8. The paper strip according to claim 6, wherein the marks arearranged on the rear side of the region to be printed.
 9. The paperstrip according to claim 6, wherein the marks are arranged on twolongitudinal sides of the paper strip.
 10. A method for aligning alongitudinally displaceable paper strip with respect to a printing unitin a tachograph, comprising the steps of: aligning the printing unitwith respect to a reference line of a region to be printed, whichreference line extends longitudinally over the paper strip, and sensinga series of marks which are arranged on the paper strip transverselywith respect to the direction of movement and are of different lengthsby a sensor, wherein a control device detects an offset of the printingunit with respect to the reference line from the signal sequence of thesensor and actuates the printing unit in order to compensate for theoffset.
 11. The method according to claim 10, wherein a line is printedout during a first adjustment of the printing unit of the tachographwith respect to the reference line of the paper strip, in that an offsetof the line with respect to the reference line is measured and is inputinto the control device, and in that the control device compensates forthe measured offset during the actuation of the printing unit.